Refrigerant R22 (CCl2F2) is widely used for residential and commercial air conditioning, as well as commercial refrigeration and has been commonly used with a mineral oil lubricant.
Driven by the 1992 amendment to the Montreal Protocol that calls for the phase-out of HCFCs, refrigerant manufacturers developed HFC alternatives. Original Equipment Manufacturers selected R404A/R507, R407C and R410A to replace R22. They found, however, that system changes were necessary for this conversion and made appropriate design changes to meet application requirements and regulatory demands.
Particular attention has been directed at blends of R134a (1,1,1,2-tetrafluoroethane) along with R125 (pentafluoroethane) as alternatives for R22 refrigerants in air conditioning and refrigeration systems. Commercial formulations of these two refrigerants also involve the use of isobutane (R600a). See, Table 1 below. See also U.S. Pat. Nos. 6,606,868 and 6,655,160 the disclosures of which are herein incorporated by reference.
TABLE 1Nominal CompositionDesignationR125 (%)R134a (%)R600a (%)R-422A85.111.53.4R-422B55.042.03.0R-422C82.015.03.0R-422D65.131.53.4
The R422A-D refrigerants have proven to be valuable retrofit refrigerants for R22 systems because they are compatible with mineral oil lubricants. Such compatibility can make these refrigerants economically attractive retrofit options by potentially avoiding the time and expense of changing lubricant types and the attendant changes to seals and other polymeric surfaces that might have been swelled by the mineral oil.
Like many refrigerants that are designed to replace R22 refrigerants in existing equipment, the use of R422A-D refrigerants results in a significantly higher mass flow to provide the same cooling capacity as R22. Thus, the desire to use one of R422A-D to retrofit equipment designed for R22 can require the replacement of expansion devices, distributor nozzles or even line sets. Lower capacity also means longer periods of operation to achieve the same level of cooling. See Spletzer et al., “Refrigerants for R-22 Retrofits”, http://www.arkema-inc.com/literature/pdf/1035.pdf (2011).
It would be desirable to have a replacement refrigerant for retrofitting R22 equipment in air conditioning and refrigeration systems that was compatible with mineral oil, like the existing R422A-D formulations, but which would exhibit a similar cooling capacity and required mass flow rate that would not necessitate replacement of the expansion devices in the system.